The present invention relates to an implantable device for occluding a duct, especially a blood vessel, in the body of a living being, which device is of the type comprising a flexible, elongate plate to be fixed around the duct, a plurality of communicating bulbs which are arranged on one side of the plate and have variable volume, and a connection for supplying fluid to the bulbs for occluding the duct and for evacuating fluid from the bulbs to open the duct after the occlusion.
A known approach for treating cancer of the liver is ischaemic treatment, in which the arterial blood flow to the tumor cells is occluded for limited periods of time. The publication "Repeated Liver Ischemia with an Implantable Vascular Occluder", Advances in Regional Cancer Therapy, III Int. Conf. Ulm 1987, pp 20-26 (Karger, Basel 1988) discloses a device for occluding the blood flow through a blood vessel. This device comprises a flexible, elongate strip or plate of silicone, on which a balloon is centered. In connection with a surgical operation, the plate is applied around the blood vessel to be occluded, and its ends are sewn together so as to provide a ring or cuff of suitable diameter around the blood vessel. The balloon is connected to a silicone catheter, in turn connected to a subcutaneous injection port with a self-sealing silicone membrane which permits repeated puncture and injection of fluid. In ischaemic treatment, the balloon is filled with fluid, thus increasing its volume and compressing the blood vessel, so as to obstruct the supply of blood. When the blood vessel is again to be opened, the fluid is sucked out of the balloon.
This prior art device suffers, however, from a number of drawbacks.
In particular, in some cases the blood flow is not completely occluded since the compression occurs only from one side of the blood vessel. In an improved device, the compression of the blood vessel should occur concentrically. Experiments have shown that if the device described above is modified such that the balloon extends around the entire blood vessel, creases are often formed, shutting off certain parts of the balloon and resulting in incomplete evacuation thereof. Moreover, high local pressures may arise, with a consequent risk of pressure-induced necroses.
Other drawbacks of the known device relate to the fixing of the plate around the blood vessel. For instance, it is difficult to attach the device in a manner which is neither too tight, nor too loose. If, on the one hand, it is attached too tightly, there is an obvious risk of permanent total occlusion. If, on the other hand, it is attached too loosely, the balloon may risk, when being inflated, to "roll out" on either of the sides of the plate, whereby the compression becomes insufficient. It is also difficult to adjust the known device to different blood vessel diameters.
Further, the balloon may risk to become damaged by the needle used for sewing together the plate ends. Repeated inflation of the balloon, which may occur a vast number of times, also leads to substantial strain on the sutures which may easily become loose or cut into the plate.
U.S. Pat. No. 4,399,809 discloses a device for providing a substantially concentric occlusion of a blood vessel. This device, which is an artificial sphincter, comprises a flexible strip having at least one row of inflatable chambers or bubbles extending in the longitudinal direction of the strip and communicating with each other. In use, the chambers are filled with and emptied of fluid through a hose passing from one of the chambers to a chamber in a manually-operated pump. This device does not solve the problems related to the fixing of an occlusion device around a duct.
DE-3,715,875 describes a device for occluding a body vessel, comprising a catheter provided with two spaced-apart bellows in fluid communication with the catheter. The catheter is to be placed in a loop around a body vessel, the fixing of the catheter being effected by means of a figure eight-shaped holder which is fixed to the catheter before the bellows and in which the free end of the catheter located on the other side of the bellows is inserted.
In this case, the occlusion of the body vessel is brought about by clamping the body vessel between the two planes defined by the bellows, whereby the walls of the body vessel are pressed out sideways.